Protanopia Test (Red-Blind)
This Ishihara-style test screens for protanopia, the complete absence of red-sensitive (L) cones. If you have protanopia, you will have difficulty seeing the numbers hidden in these plates because the foreground and background colors fall along the red-green confusion axis.
Before you begin
Set up your screen and lighting
Display conditions can materially change an online color vision result. Take a moment to check these items before starting.
- Use a color screen at its normal brightness, viewed straight on.
- Turn off Night Shift, blue-light filters, grayscale, and color filters.
- Use neutral room lighting and avoid glare on the display.
- Wear your usual prescription glasses or contacts, if applicable.
- Use your first impression and answer each plate within about 5 seconds.
What This Test Screens For
Protanopia is a form of dichromacy where the L-cones (long-wavelength, red-sensitive) are entirely absent. This test uses pseudoisochromatic plates designed along the red-green confusion axis. If you cannot distinguish the colored dots that form the hidden number from the background dots, it suggests a red-green color vision deficiency consistent with protanopia or protanomaly.
Limitations of This Test
This online screening cannot distinguish protanopia from protanomaly (red-weak) or from deutan-type deficiencies (deuteranopia, deuteranomaly). All red-green deficiencies produce similar patterns on Ishihara-style plates. A definitive diagnosis requires an anomaloscope test administered by an eye care professional. Screen calibration, brightness, and ambient lighting also affect accuracy.
What to Expect
You will see 10 circular plates filled with colored dots. Each plate contains a hidden number that people with normal color vision can read. Enter the number you see, or indicate that you see nothing. The test takes 2-3 minutes.
How Does This Protanopia Test Work?
Each plate uses colors carefully chosen along the protan/deutan confusion line. The number is rendered in warm tones (oranges, reds) against a background of cool-shifted tones (greens, olives) at matched luminance. A person with normal trichromatic vision can distinguish the hue difference and read the number. A person with protanopia lacks the L-cones needed to differentiate these hues, so the number blends into the background.
Understanding Protanopia
Protanopia affects approximately 1% of men and 0.01% of women. It is caused by the complete absence of functional L-cones due to mutations in the OPN1LW gene on the X chromosome. People with protanopia see the world primarily in blues and golds, with reds appearing very dark or nearly black. The condition also causes a characteristic brightness reduction for red, orange, and yellow-green colors.
Frequently Asked Questions
Can this test tell me if I have protanopia specifically?
This test screens for red-green color vision deficiency but cannot distinguish protanopia from protanomaly, deuteranopia, or deuteranomaly on its own. All four conditions cause difficulty reading Ishihara-style plates. For a specific diagnosis, you need an anomaloscope test from an eye care professional.
What score indicates protanopia?
The first plate is a demonstration and is not scored. Identifying 8 or 9 of the 9 screening plates suggests normal red-green discrimination on this screen. Missing two or more is a reason to repeat the test under good conditions and consider a professional examination. This online screen cannot determine subtype or severity.
Is protanopia the same as being completely color blind?
No. Protanopia is specifically a red-blind condition where only the red-sensitive cones are absent. People with protanopia can still see blues, yellows, and many other colors. Complete color blindness (achromatopsia) is a much rarer condition in which all cone types are nonfunctional.
Learn more about this condition
Related Tests
Deuteranopia Test (Green-Blind)
This Ishihara-style test screens for deuteranopia, the complete absence of green-sensitive (M) cones. People with deuteranopia cannot distinguish the hidden numbers because the plate colors lie along the red-green confusion axis that their vision cannot resolve.
Protanomaly Test (Red-Weak)
This Ishihara-style test screens for protanomaly, a mild form of red-green color blindness where the red-sensitive (L) cones are present but spectrally shifted. People with protanomaly may have difficulty with some or all of these plates depending on the severity of their condition.
Red-Green Colorblind Test
This Ishihara-style test screens for all types of red-green color blindness, including protanopia, deuteranopia, protanomaly, and deuteranomaly. Red-green color deficiency is the most common form of color blindness, affecting approximately 8% of men and 0.4% of women worldwide.